Experts say you can trick your mind into helping you lose weight

Video: Experts say you can actually trick your mind into thinking you’re full, even when you’re eating less, by thinking about factors like the plate you use. NBC national investigative correspondent Jeff Rossen reports at a surprising social experiment.

Most of us eat until we're full. But experts say there's a way to feel full faster and eat less without dieting — by thinking about the plate you use, the utensil, and the order of what you eat. And they say they can prove it.

TODAY threw a free buffet lunch for viewers — with cameras rolling. What they didn't know is that they were participating in a social experiment.

Cornell University professor Brian Wansink, former executive director of the USDA's Center for Nutrition Policy and Promotion, helped design and run the experiment to show he could manipulate how much the lunch guests ate by tricking their minds. "How much we eat and what we eat almost has nothing to do with how hungry we think we are," Wansink said. "It's all psychological.

"It's about the things around us," he added. "It's about the order of the food, the size of the plates, the size of a serving spoon."

TODAY split the lunching viewers into two groups, of 12 participants each. For the first group, the buffet was laid out with fruit and salad first, then fatty pasta dishes at the end. The first group was given normal size plates and normal serving spoons.

TODAY cameras captured them piling on the healthy stuff, leaving not much room on their plates for the gooey pasta. "The first food you see in a buffet is a trigger food," Wansink explained. "It triggers every other decision that you make after that. So if it's healthy, everything else you're going to take is more likely to be healthy. "

Behind the scenes, TODAY tracked how much the first group ate. When they were done, the buffet table was reset for group two — with some changes.

The order of the food was switched so that the healthy stuff went in back while the fatty stuff was placed at the beginning. In addition, group two was given slightly bigger plates and serving spoons. But the food itself was exactly the same.

TODAY cameras captured the second group heaping spoonfuls of pasta right out of the gate, their plates piled high. "They are bingeing on that pasta because it's the first thing they see and, as we know, it's the trigger food," Wansink observed.

So where you start in the buffet line matters. "What we find is, about 70 percent of what people are taking are the first three foods they see," Wansink said.

When they'd had their fill, TODAY brought both groups together for the big reveal. "We've been secretly weighing the food in the back to see what you ate," they were told. The results: The group with the bigger plates and serving spoons ate a jaw-dropping 56 percent more food, most of it pasta.

The group with the smaller spoons ate an average of 890 calories per person in pasta, while group two, with the bigger plates, consumed an average 1,520 calories per person in pasta alone.

"I thought because I had the larger plate and it was emptier, I wasn't eating as much," commented one woman from group two. "I thought I was doing good."

"We eat with our eyes and our mind," Wansink said. "Not our stomach."

Wansink says that even just using smaller plates will trim you down, losing you one to three pounds a month, and you won't even know you're eating less. And it doesn't work just in restaurants; you can use these tips at home with your family. For example: Serve the healthier foods first — bring out the salad before you bring out the main course. It makes a big difference.